Multiple Input Multiple Output (MIMO) increases the efficiency of data transmission and reception using multiple transmit antennas and multiple receive antennas. A receiver receives data through multiple paths when multiple antennas are used, whereas the receiver receives data through a single antenna path when a single antenna is used. Accordingly, MIMO can increase a data transmission rate and throughput and improve coverage.
Research on Coordinated Multi-Point (CoMP) for improving throughput of a UE located at a cell boundary by applying improved MIMO to a multi-cell environment is actively performed. The CoMP system can decrease inter-cell interference in a multi-cell environment and improve system performance. CoMP schemes include joint processing (JP) which groups multiple neighboring cells into one group and performs joint processing on the neighboring cells by regarding the cell group as a virtual MIMO system, and cooperative beamforming (C-BF) for solving inter-cell interference by adjusting beam patterns among neighboring cells.
It is necessary for cooperative base stations to obtain feedback information on virtual multi-antenna channels generated between the base stations and UEs belonging to a cooperative group to effectively improve CoMP performance.